Postcuring of unsaturated stereolithographic specimens using aqueous initiating baths

• US 4,972,006 A
• Filed: 09/08/1988
• Issued: 11/20/1990
• Est. Priority Date: 09/08/1988
• Status: Expired due to Fees

• Current Assignee: DSM Resins BV (DSM-Firmenich AG)
• Original Assignee: DeSoto, Inc. (Overstock.com Incorporated)
• Inventors: Murphy, Edward J., Krajewski, John J., Ansel, Robert E.
• Primary Examiner(s): McCamish, Marion C.
• Assistant Examiner(s): BERMAN, SUSAN W
• Application Number:
  US07/241,881
• Time in Patent Office: 803 Days
• Field of Search: 522/121, 522/85, 522/84, 522/24, 522/28, 427/54.1, 427/340, 427/341, 427/393.5
• US Class Current: 522/121
• CPC Class Codes: B29C 2071/0018 Absorbing ingredients, e.g. drugs, flavourings, UV screeners, embedded in the articles
• CPC Class Codes: B29C 64/124 using layers of liquid which are selectively solidified
• CPC Class Codes: B29C 64/30 Auxiliary operations or equipment
• CPC Class Codes: B29C 71/0009 using liquids, e.g. solvents, swelling agents spectacle cases, e.g. for cleaning contact lenses A45C11/04; disinfecting or sterilising contact lenses A61L12/00, using liquid substances A61L2/20; cleaning involving the use of liquid in general B08B3/00; for hydrating contact lenses B29D11/00067
• CPC Class Codes: B29C 71/02 Thermal after-treatment B29C71/0063 and B29C71/0072 take precedence
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 40/20 Post-treatment, e.g. curing, coating or polishing
• CPC Class Codes: B33Y 70/00 Materials specially adapted for additive manufacturing
• CPC Class Codes: C08F 4/40 Redox systems

Abstract

A method of curing a three-dimensional specimen of preformed cross-linked polymeric material containing polymerizable ethylenically-unsaturated material is provided in which the specimen is immersed in water having dissolved therein an amount of a water-soluble organic free-radical polymerization catalyst effective to transfer a polymerization-initiating amount of the catalyst into the preformed cross-linked polymeric material. This specimen containing the water-soluble organic free-radical polymerization catalyst is heated to a temperature causing polymerization, and is maintained at that temperature while the cure is completed. The aqueous bath preferably contains a catalyst mixture which includes a catalyst of oxidizing character in admixture with a reducing agent, such as an amine, and is maintained at a polymerization temperature of from 60° C. to 100° C. so that immersion of the specimen in a single bath completes the cure.

Claims

1. A method of curing a three-dimensional specimen of preformed cross-linked polymeric material containing within itself polymerizable ethylenically-unsaturated material therein comprising the steps of immersing said specimen in water having dissolved therein an amount of a water-soluble organic free-radical polymerization catalyst effective to transfer a polymerization-initiating amount of said catalyst into said preformed cross-linked polymeric material, subjecting said specimen containing said water-soluble organic free-radical polymerization catalyst to a temperature sufficient to cause polymerization of the ethylenically unsaturated material, and maintaining said specimen at said polymerization temperature to cure the same.

2. A method as recited in claim 1 in which said specimen is also immersed in water having dissolved therein a reducing agent.

3. A method as recited in claim 1 in which said specimen is immersed in water having a temperature of at least about 60°

C. while it is polymerized.

4. A method as recited in claim 1 in which said specimen is made by the photopolymerization of ethylenically unsaturated material a portion of which is polyethylenically unsaturated to provide a gelatinous cross-linked polymeric matrix containing ethylenically unsaturated material.

5. A method as recited in claim 4 in which said cross-linked polymeric matrix contains monoethylenic monomers.

6. A method as recited in claim 1 in which said catalyst is a mixture of a water-soluble organic free-radical polymerization catalyst of oxidizing character and a reducing agent which are present in an aqueous bath heated to a temperature causing polymerization of said ethylenically unsaturated material.

7. A method as recited in claim 6 in which said reducing agent is a water-soluble amine.

8. A method as recited in claim 7 in which said amine is an hydroxy-functional amine.

9. A method as recited in claim 6 in which said catalyst comprises a water-soluble organic free-radical peroxide polymerization catalyst and an amine, said bath being heated to a temperature of at least 60°

C.

10. A method as recited in claim 9 in which said aqueous bath is maintained at a temperature in the range of 80°

C. to 100°

C.

11. A method as recited in claim 1 in which said specimen is immersed in an aqueous bath containing a water-soluble organic free-radical azonitrile polymerization catalyst, said bath being heated to a temperature causing polymerization of said ethylenically unsaturated material.

12. A method as recited in claim 1 in which said bath is maintained at a temperature of from 80°

C. to 100°

C.

13. A method as recited in claim 2 in which said specimen within said aqueous bath is subjected to ultrasonic agitation to remove liquid materials clinging to said specimen.

14. A method as recited in claim 13 in which said ultrasonic agitation is carried out in an aqueous mediuim in which polymerization does not occur.

15. A method as recited in claim 1 in which said bath contains surfactants and/or water-miscible organic solvents to aid wetting said specimen.

16. A method of curing a three-dimensional specimen of preformed cross-linked polymeric material containing within itself polymerizable ethylenically-unsaturated material made by the photopolymerization of ethylenically unsaturated material at least a portion of which is polyethylenically unsaturated to provide a gelatinous cross-linked polymeric matrix containing ethylenically unsaturated material, comprising the steps of immersing said specimen in water having dissolved therein a water-soluble organic free-radical polymerization catalyst of oxdizing character and an amine, said water being heated to a temperature of at least 60°

C., and holding said specimen in said heated bath to cause polymerization of said ethylenically unsaturated material to thus cure said specimen, and withdrawing the cured specimen from said bath.

17. A method as recited in claim 16 in which said amine is an hydroxy-functional amine and said bath is maintained at a temperature of from 60°

C. to 80°

C.